Hospital volume and vascular surgical specialization are associated with in-hospital mortality after invasive treatment of Type B aortic dissections: - Secondary data analysis of German hospital episode statistics from 2010 to 2023.

Abstract

Type-B aortic dissections (TBAD) require complex surgical or endovascular treatment in a subset of patients. Whether hospital caseload or vascular specialization might affect perioperative outcomes remains unclear. This study evaluates the association between annual hospital volume, vascular surgical specialization, and in-hospital mortality after TBAD treatment in Germany. We performed a nationwide retrospective analysis of German Diagnosis-Related Group (DRG) hospital episode data from 2010-2023. All surgically or endovascularly treated TBAD cases were identified through International Statistical Classification of Diseases and Related Health Problems, 10^th revision, German Modification (ICD-10-GM) and procedural (OPS) codes. Hospitals were stratified into four annual caseload categories (≤5, 6-10, 11-20, >20 cases). Primary outcome was in-hospital mortality; secondary outcomes included major perioperative complications. Multilevel logistic regression (random intercepts for hospital and year) was performed to assess the association of hospital volume and vascular surgery specialization of treating surgeon with mortality, adjusting for demographics, comorbidities, and treatment modality. A total of 18,400 treated TBAD cases were identified. Very-high-volume hospitals (>20 cases/year) treated 36.9% of all cases, while low-volume hospitals (≤5 cases/year) accounted for 67.4% of treating institutions, but only for 22.3% of procedures. Overall, in-hospital mortality was 9.1%, decreasing from 10.1% in low-volume to 7.8% in very-high-volume hospitals. In risk-adjusted analyses, low- and medium-volume hospitals showed significantly higher in-hospital mortality (OR 1.30, 95% CI: 1.05-1.60, p=0.016 and OR 1.32, 95% CI: 1.06-1.64, p=0.013 vs. very-high-volume, respectively), while treatment in vascular surgery departments was associated with reduced in-hospital mortality (OR 0.44, 95% CI: 0.36-0.54, p<0.001). Higher hospital caseload and vascular specialization were independently associated with improved in-hospital survival after TBAD treatment. Findings support centralization of complex aortic care and emphasize that both procedural volume and dedicated vascular expertise contribute to optimal outcomes.